Process for the recovery of nitrogen oxids



P. A. GUYE. PROCESS FOR THE REGOV EBY 0F NITROGEN OXIDS. APPLICATION FILED MN. 4.:1919.

1331,104. Patented Feb. 17, 1920.

ATTORNEYS the coils and diminishes the efficiency of the apparatus.

I UNITED S A E Parana? our:

I PHILIPPE AUGUSTE GUYE, or snnnv'e, 'swirznnnaun.

" rnocnss non THE fnncovnnr or ni'rnoenn earns.

' pplica ion filed January 4;].919.

To, all whom it may concern Be 1t knownthat I, PHILIPPE Aucus'rn GUYE, a citizen of Switzerland, residing at Geneva, Switzerland, have invented new -and useful lmprovements in Processes for the" Recovery of Nitrogen Oxids, ofwhich the following is a specification;

This invention relates to a novel and useful process of recovering nitrogen oXids, and particularly such as are produced by subjecting a dry mixture of nitrogen and oxygen to the action of an electric rrc.

As is well known, when a gaseous current gconsistingof' a dry mixture of nitrogen and 'oxygen,'either in the proportions of atlnospher1c air or any other proportions, is sub jected to the action-of an. electric arc, there 'is produced nitric oxid, (NO) which pass ing outwith the gaseous current is trans formed by cooling into nitrous anhydrid (N 0 and into nitrogen peroXid"(N Q,), 'or NO,. 'These substances'constitute what are generally termed nitrous oXids. In the presence of an excess of oxygen, and within a short period of time, in some it-istances from one to three minutes, the oxidation is nearly complete andv the nitrous oxide are composed almost exclusively of peroxid-of u1ne) its liquefaction cannot be completed except by reducing the temperature of the .whole gaseous mass to 80 degrees C. (more or less). Since peroXid of nitrogen solidifies at +7 degrees C. the result is that the condensing coils of the apparatus commonly employed in carrying out this ordinary method of recovery are rapidly covered wit solid peroxid of nitrogen, which, obstructs To avoid this disadvantage it .has been proposed to use two condensing 'apparatuses working alternately, one being i employed for condensation while the other is used in order to re-liquefy by heat the Specification of. Letters "Eatent.

Fate? Serial no. sear/a7.

will form with such peroxid of nitrogen a -nnJ-f*lure non-congealable'at a low temperature. For instance, arbon tetrachlorid has been employed for this purpose, and from the resulting mixture the peroxid of nitrogen is recovered by fractional distillation.

It will tl'ltBlGfOld be noted that such methods or processes of recovering nitrogen oxide are complicated, tedious and expen sive.

The purpose of the present invention is to obviate the above recited. disadvantages by providing a simple, economical and ellicient process for recovering these oxide.

In the practice of my invention I accomplish this purpose by regulating th'etime for the oxidation of the nitrogen peroXid gas after its formation in the electric arc, in such manner that the moment the gases reach the condenser the nitrous oXids, composed of peroxid of nitrogen in the presence of a certain quantity of nitrous anhydrid suflicient for the mixture of both compounds,

remain liquid-at the determined tempera fure of liquefaction, that is, degrees (1.,

as heretofore mentioned.

The pure nitrous anhydrid. remaining liquid below -l00 degrees Ci, and easily dissolving in every proportion the peroxid of nitrogen, a relatively small proportion of nitrous anhydrid is suflicient to obtain the desired result. As a convenient proportion, we may resort to that which corresponds to about equal parts of the two substances, and with even smaller quantities of nitrous anhydrid the mixture will remain liquid at less than 0 degrees C.

If the oxidation of the nitric OXlCl (NO has been satisfactorily regulated to this condition, the liquefaction of the nitrous oxide may be effected continuously and in the same apparatus, without the deposit of solid peroxi'd of nitrogen and without obstructing the coils of the apparatus, and'fi'zatheri \OI'G, the necessity of following the practice of employing a solventwhicli will not solidify and then separation by fractional distillation is avoided. So far as concerns the nitrous OXlClS (the mixture of nitrous anhydrid and nitrogen peroxid) liquefied and collected in the condenser, it is sufiicient to treat the same with oxygen in order to effect a total transformation of these oXids into 'oeroXid of nitrogen, or else to transform them into nitrous a-nhydrid withnitric oxid (NO), or to transform them into COI1C6I1-' condensation, in this case the period or dura ation of oxidation being' diminished. The opposite course should be taken when it is desired to obtain peroxid of nitrogen in the main. r l

In order to regulate the time for the oxidation of the nitric oxid, as mentioned, .a simple apparatus, such as is shown in the drawing may be employed- This comprises an oxidizing chamber A-divided by partitions into a selected number of compartments shown at 1'23 and Al, The gas enters through the main line inlet -5 and leaves through the outlet 6, so far as concerns its travel with relation to these compartments.

Suitable valves, shown at 7,8, 9 and 10 are employed for the purpose of putting any compartment or compartments out of communication with the gas main, as may be desirable. The compartments are arr: nged in such manner as to facilitateintroduction or removal of the gases; to regulate the composition of the,gaseous mixture of ni-- trogen and oxygen according to the temperature of the gases,especially 'to obtain nitrous anhydrid, or, on the other hand, to obtain nitrogen peroxid, and finally by determining the power absorbed by the arc furnaces, to' vary between wide limits the capacity of the oxidizing chamber.

The cooling of the gases may be accomplished in any preferred manner, as for instance, by the circulation of the gases in a suitable cOil 1l externally cooled either by a constantly circulating bath-of cool liquid, such as toluene or petroleum, or by cool air, or by any other means. The cooling may also be accomplished by compression of nitrogen from a mixture thereof with other gases by oxidizing the oxids and subse quently liquefying them by refrigeratlon, the step which consists in regulating the oxidation of said oxids so as to produce a mixture of oxids of nitrogen which will not solidify above zero degrees 'centigrade.

2. In the process of recovering oxids of nitrogen from a mixtu're thereof with other gases by oxidizing the oxids and subsequently liquefying them by refrigeration. the step which consists in regulating the oxidation of said oxids to, produce a mixture of nitrous anhydrid and peroxid of nitrogen which will not solidify above zero degrees centigrade.

3. In the process of recovering oxids of nitrogen from a mixture thereof with other gases by oxidizing the oxids and subsequently liquefying them by refrigeration,v

the. steps which consist in oxidizing the oxids by passing them through an oxygencontaining chamber and invarying the size of-said chamber to' vary the extent of oxidization, so as to produce EL IHIXtUI'G of different oxids which will not solidify above zero. degrees centigrade.

4.: In the process of recovering oxids of nitrogen from a mixture thereof with other [gases by oxidizing the oxids and subsequentlyliquefying them by refrigeration, the steps which consist in providing 1 plu ralit-y of oxygen-containing compartnient-s, and passing the oxids through .i selected number of said compartments in succession,

the number of compartments "ISGCl being determined by the extent of )X1tllZ.ltl011 ilQ- sired, so that the gases passing to the refrigeratin'g means will contain a mixture 'of oxids of nitrogen which will not solidify above zero degrees "Centigrade. I

5. In the process of'recovering oxids of nitrogen from a mixture thereof with other gases by oxidizing-the oxids and subsequently liquefying them by refrigeration,

, the steps which consist in providing a' plurality of oxygen-containing compartments, and passing the oxids through a'selected number of said compartments in succession the number of compartments used being de-. ermined by the extent of oxidization d sired, so that the gases passing to the refrigerating means will contain' a mixture of centigrade. v v GJTheherein described process For the transformation vof a variety of oxids of ni trogen, mixed with other gases. into a single ,perox'id of nitrogenwitl nitrousanhydrid, 1 which will not solidify-above zero degrees solidifying at temperatures above zero degi'ees centigrade;'-next cooling the mixture to liquefy said oxids without liquefying the remaining gases; then segregating theliquefied oxids, and finally. chemically treating said oxids to vary the amount of oxygen in l the molecules of all but one of said ox ds to reduce them to the same chemical character as the unchanged oxidtpi'oducing a single oxid as the product.

In testimony whereof I have hereunto set my hand.v

PHILIPPE AUGUSTE GUYE. 

